Slackless rotary drawbar assembly

ABSTRACT

The present invention provides a slackless rotary drawbar assembly of simple yet rugged construction. The drawbar assembly preferably consists of five parts: a rotary drawbar, a rotary drawbar support housing, a bottom support casting, a rear support block, and a slack adjustment wedge. The rotary drawbar support housing is welded into the center sill of a railroad car and supports the rotary drawbar so as to permit unrestricted universal movement of the drawbar through the range of movement required under normal operating conditions. The rotary drawbar has an enlarged truncated convex spherical end portion which mates with concave surfaces formed in the support housing and the bottom support casting. The bottom support casting is secured to the center sill and holds the drawbar in the support housing. The truncated convex spherical end portion also mates with a concave surface formed in the rear support block. A rear tapering surface of the rear support block is engaged by a mating gravity-activated wedge which is arranged to move vertically to compensate for wear and to maintain a slackless relationship of the parts that interconnect the drawbar with the train car. The assembly of the present invention provides an economy in design by reducing the number of parts required to obtain the advantages of prior art slackless rotary drawbar assemblies. Furthermore, the present invention is less subject to damaging friction and premature part wear and is more easily and accurately assembled and disassembled than prior rotary drawbar assemblies.

This application is related to U.S. patent application Ser. No. 352,932,filed May 17, 1989, still pending and having a common assignee andinventorship herewith.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a drawbar assembly for connecting togetherrailroad cars, in general, and, more particularly, to a drawbararrangement embodying a simplified construction and arrangement of partsthat includes a drawbar with a truncated convex spherical end containedbetween a front draft bearing surface formed integrally with a drawbarsupport housing which is secured to a center sill and a rear supportblock which is supported against the housing by a gravity-activatedwedge.

2. Description of the Prior Art

As is known, most prior art railroad coupler assemblies are relativelycomplicated and include a draft sill, draft gear, yoke, follower block,striker, pin or coupler connection and the coupler itself and itsassociated components. Such conventional coupler arrangements have adegree of free and cushioned slack. That is, there is a certain amountof free "play" between the coupler components when the load changes froma draft to a buff load, and vice versa. At the same time, the draft gearacts as a spring mechanism to cushion impacts between adjacent cars.Research has indicated that eliminating the free and cushioned slackwithin a train can eliminate over the road train action forces due to"run-ins" and "run-outs". The magnitudes of these forces are large andcause significant wear and tear on the rolling stock and in someinstances are severe enough to cause derailments.

Furthermore, in conventional coupler assemblies, the key or pinconnection of the coupler to the yoke is at a relatively long distancefrom the kingpin about which the wheel truck rotates. In negotiatingcurves, particularly under buff loading conditions, this gives rise torelatively large lateral forces which can cause derailments. The same istrue when jackknifing occurs under buff loads with lateral forcesattempting to rotate the cars about their centers.

An improvement to the aforesaid conventional coupler assemblies wasdisclosed in U.S. Pat. No. 4,580,686, the disclosure of which isincorporated herein by reference. While not limited thereto, thatpatent, as well as the present invention, was particularly adapted foruse in unit train applications where cars are coupled and uncoupled forperiodic maintenance and repair only. Such cars are not subjected dailyto impact forces associated with bumping encountered in classificationyards and, therefore, do not require cushioning devices such as draftgears.

Specifically, that patent provided a drawbar arrangement for couplingrailroad cars each having a center sill and trucks at its opposite ends,the trucks being pivotal about vertical kingpins. The arrangementincluded a drawbar having an enlarged spherical butt end portiondefining essentially convex spherical buff and draft load surface, arear support block having a tapered rear surface and concavesubstantially hemispherical buff load bearing surface adapted to engagewith the convex buff load bearing surface of the butt portion, a slackadjusting wedge for engaging the tapered surface of the rear supportblock, means for transferring buff loads from the slack adjusting wedgeto the center sill, a front draft block having a concave andsubstantially hemispherical draft load surface adapted to engage withthe convex draft load surface of the enlarged spherical butt endportion, the front draft block including an annular draft load surfaceopposite the hemispherical draft load surface thereof, a wear blockhaving an annular draft load surface adapted to engage the annular draftload surface of the front draft block, and means supported by the centersill for transferring a draft load from the wear block to the centersill.

Preferably, the drawbar arrangement of U.S. Pat. No. 4,580,686 providedthat the draft block and the wear block each have an opening wherein theshank of the drawbar extended in a direction which was generallyopposite the kingpin. The aforesaid means supported by the center sillincluded a plurality of draft stop lugs supported by the center sill. Asill bottom plate was preferably secured to the center sill forsupporting one of the plurality of draft stop lugs. The center sillincluded spaced-apart sill side walls extending along opposite sides ofa sill roof wall. The drawbar arrangement preferably further included acarrier plate supported by the center sill opposite the roof wallthereof for supporting the rear support block, front draft block and thewear block between the side walls of the center sill. The taperedsurface of the slack adjusting wedge was preferably arranged to extendin a vertical direction along the height of the side walls of the outersill. The tapered thickness of the wedge was greater at the top thereofthan at the bottom for movement under the force of gravity between therear support block and the lugs supporting the wedge on the center sill.An opening in the front draft block was preferably longer in thevertical direction than in the horizontal direction, whereby the draftfront block rotated with the drawbar shank portion in a horizontal planebut not in a vertical plane. Moreover, the rear support block and frontdraft block rotated in an endless manner about an axis extendingsubstantially along a central longitudinal axis of the shank relative tothe convex spherical buff and draft load surfaces. The pivotal action atthe end connections facilitated rotation, and permitted 360° rotationfor negation of horizontal and vertical track curves as well as rotarycar dumping.

With an arrangement of that sort, free and cushioned slack waseliminated form the interconnection between cars, thus eliminatingundesirable longitudinal train action forces and reducing the risk ofderailment. The slackless connection between cars provided therebyeliminated run-in and run-out of slack between cars in reversals ofdraft and buff train actions. That also eliminated the generation oflarge forces due to relative accelerations between cars, thus reducingwear and damage to car components, lading and locomotives, therebyreducing maintenance cost. The design of the drawbar reduced anestimated 650 pounds from the tare weight of the car and eliminatedcouplers, yokes, cushioning devices and strikers. At the same time, thestructure forming the pivotal connection at each end of the drawbarcould be incorporated into existing center sills without modification ofthe center sills. Moreover, the site at which the structure used tointerconnect the end of the drawbar with the center sill could belocated at any desired location but preferably rearwardly of the car toreduce lateral wheel force components. By moving the pivot point of thedrawbar toward the center line of the bolster, car tracking throughtight radius curves was enhanced while reducing the potential for trackoverturn plus wheel wear. That invention further utilized agravity-activated wedge which was arranged to move vertically tocompensate for wear and maintain a slackless relationship of parts thatinterconnected the drawbar with the car.

While the structure disclosed in U.S. Pat. No. 4,580,686 represented animprovement over prior conventional coupler assemblies, it requiredrather difficult assembly and disassembly and was subject to significantwear caused by friction.

For example, if either the front load bearing block or the wear blockneeded repair or replacement, a weld or other connecting means joiningoppositely-directed shanks which formed the drawbar had to first bedestroyed or otherwise removed to release the shanks from one another.The drawbar could then be removed from the center sill by removing thesill bottom cover plate which held the front and rear load bearingblocks about the enlarged spherical end portion of the drawbar. Once thedrawbar was removed from the sill, the front block and/or the wear blockwere then slidably removed from the shank. Then, a repaired or areplacement front block and/or wear block was slid back onto the shankof the drawbar. Upon completion of the maintenance, the drawbar assemblywas reassembled and the oppositely-directed shanks were then rewelded orotherwise connected to form a continuous drawbar.

Also, the large area of surface contact between the spherical butt endportion of the drawbar and mating spherical portions of the front draftblock and rear buff block led to the creation of significant frictionbetween and, consequently, premature wearing and failure of thosecontacting parts.

An advantage exists, therefore, for a slackless rotary drawbar assemblywhich is easily assembled and disassembled and which has a high degreeof reliability.

It is therefore an object of the present invention to provide aslackless rotary drawbar assembly which is easily assembled anddisassembled.

It is a further object of the present invention to provide a slacklessrotary drawbar assembly having a reduced likelihood of premature wearand failure of its constituent parts.

Still other objects and advantages will become apparent in light of theattached drawings and written description of the invention presentedherebelow.

SUMMARY OF THE INVENTION

The present invention provides a slackless rotary drawbar assembly ofsimple yet rugged construction. The drawbar assembly preferably consistsof five parts: a rotary drawbar, a rotary drawbar support housing, abottom support casting, a rear support block, and a slack adjustmentwedge.

The rotary drawbar support housing is welded into the center will of arailroad car and supports the rotary drawbar so as to permitunrestricted universal movement of the drawbar through the range ofmovement required under normal operating conditions.

The rotary drawbar has an enlarged truncated convex spherical endportion which mates with concave surfaces formed in the support housing,the bottom support casting, and the rear support block. The bottomsupport casting is secured to the center sill and holds the drawbar inthe support housing. A rear tapering surface of the rear support blockis engaged by a mating gravity-activated wedge which is arranged to movevertically to compensate for wear and to maintain a slacklessrelationship of the parts that interconnect the drawbar with the traincar. The assembly provides an economy in design by reducing the numberof parts required to obtain the advantages of prior art slackless rotarydrawbar assemblies. Furthermore, the construction according to thepresent invention is less subject to damaging friction and prematurepart wear and is more easily and accurately assembled and disassembledthan prior rotary drawbar assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a prior art railroad couplerarrangement showing the lateral forces which result under buff loadsduring negotiation of a curve;

FIG. 2 illustrates jackknifing motions and resultant forces exerted onrailroad cars during buff loads;

FIG. 3 is a schematic illustration of a typical prior art slacklessrotary drawbar arrangement;

FIG. 4 is an enlarged side view of the drawbar coupler arrangement ofFIG. 3.

FIG. 5 is a still further enlarged plan view of a prior art drawbarcoupling arrangement;

FIG. 6 is an elevational view, in section, taken along line VI--VI ofFIG. 5.

FIG. 7 is a front elevational view of the prior art drawbar couplerarrangement shown in FIG. 5;

FIG. 8 is an elevational view, in section, of the slackless rotarydrawbar assembly of the present invention as seen along the centrallongitudinal axis thereof;

FIG. 9 is an end view of the assembly as seen along line IX--IX of FIG.8;

FIG. 10 is an end view of the rotary drawbar of the present invention asviewed axially along its shank portion;

FIG. 11 is a plan view, in partial section, of the rotary drawbarsupport housing of the present invention;

FIG. 11A is an elevational view, in section, of the rotary drawbarsupport housing of the present invention;

FIG. 12 a view of only the bottom support casting of the presentinvention as seen in the direction of the end view depicted in FIG. 10;

FIG. 12A is a plan view of the bottom support casting as seen along lineA--A of FIG. 12;

FIG. 12B is an elevational view of the bottom support casting as seenalong line B--B of FIG. 12;

FIG. 13 is a plan view of the slack adjustment wedge of the presentinvention; and

FIG. 13A is a view as seen along line A--A of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the drawings, and particularly to FIG. 1, there isshown adjacent railway cars 10 and 12, the car 12 being on a curvedtrack section 14. Each car 10 and 12 includes a center sill 16 having acenter plate 18 which reacts on the bolster 20 of a wheel truck 22.Extending through the center plate 18 is a kingpin, not shown, whoseaxis is indicated generally by the reference numeral 24 and about whichthe truck 22 can pivot in a horizontal plane. Interconnecting the twocars 10 and 12 are conventional couplers 26 and 28 which conventionallyinclude a draft gear, a yoke, a follower block, and a pin or key couplerconnection, the axis of the pin being indicated by the reference numeral30. Each coupler can rotate in a horizontal plane about its associatedpin connection 30.

With the cars 10 and 12 under a buff load with car 10 pushing the car12, forces are imparted to the couplers 26 and 28. As can be seen inFIG. 1, the longitudinal force F₁ on the couplers is broken into alateral force F₂ and a force F₃ which extends along the axis of the car.The lateral force F₂ exerts a sideways force on the truck 22 which istaken by the wheel flanges. The force F₂ also produces a moment aboutthe kingpin 18 tending to twist the car about its center point. Thislateral force produces relatively severe stresses in the car and in somecases can cause a derailment.

In FIG. 2, a condition is illustrated wherein three cars 32, 34 and 36are undergoing jackknifing motions under a buff load. Again, lateralforces F₂ are exerted on the cars at the connection of couplers 26 and28 thereto, these forces tending to twist the cars about their centerpoints or centers of gravity.

The drawbar arrangement of the aforementioned U.S. Pat. No. 4,580,686 isshown in FIGS. 3 and 4 wherein the couplers 26 and 28 of FIG. 1 arereplaced by a drawbar 40 which is pivotally connected at the ends ofcenter sills 16. The center sills 16 are preferably reduced in length sothat the ends of the drawbar 40 pivot about axes which are as close aspossible to the center 24 of trucks for the car. As a result, thedistance between the longitudinal axis of the drawbar and the centralaxis of each car 10 and 12 is much less, resulting in a lower wheelflange to rail force produced by force F₂. In addition, there is areduced moment about the kingpin whose axes are indicated by thereference numeral 24.

With reference now to FIGS. 5-7, a specific embodiment of the drawbarassembly according to U.S. Pat. No. 4,580,686 is shown. The end portionof the center sill 16 is illustrated and takes the form of a convention"z" sill. Rear draft lugs 42 are secured as by welding to spaced-apartside walls 16A of the Z-sill. A flange 16B project. laterally from thelower edge of each side wall 16A. A slack adjusting wedge 44 is seatedagainst the rear draft lugs for supporting thereby. The wedge has avertically-tapered surface 45 in contact with a mating tapered surfaceon a rear support block 46. The wedge is arranged so that the force ofgravity acting on the wedge exerts a continuous force against the rearsupport block 46. The tapered surface on the rear support block is atthe rear thereof and opposite this surface is a concave, substantiallyhemispherical buff load bearing surface 47 adapted to engage with aconvex buff load bearing surface 48 forming part of a spherical butt endportion 49 at the end of drawbar 40. A shank 50 projects from a convexspherical draft load bearing surface 51 that is seated against ahemispherical draft load surface formed in a front draft block 52. Anannular draft load surface 53 faces a forward direction which isopposite the rearwardly-directed hemispherical draft load surface of thefront draft block. As shown in FIG. 5, the annular draft load surface iscurved between the side walls 16A of the center sill and engages with amating annular draft load surface defined on a wear block 54. The frontdraft block 52 and wear block 54 are each provided with an openingthrough which shank 50 extends.

The draft load which is transferred to the wear block is distributed tothe center sill by means which in the embodiment shown in FIGS. 5-7,comprises a plurality of lugs 55. There are four lugs illustrated, oneof which is welded to a top wall of the center sill to projectdownwardly into the space between the side walls 16A thereof and engagesthe forwardly-directed face of wear block 54. A second and third of thelugs 55 are welded to side walls 16A so that the lugs engage with theforwardly-directed face of the wear block. A fourth of the lugs iswelded to a bottom cover plate 56, the latter being secured preferablyby nut and bolt assemblies 57 to each of the flanks 16B. Thus, it can beseen that the lugs 55 extend from the side walls of the center sill andthe bottom plate 56 into the space enclosed by the sill and the bottomplate. The faces of the lugs which are opposite each other are taperedso that the shank 50 of the drawbar can move back and forth in both thehorizontal and vertical directions. The lugs efficiently transfer thepull forces from the drawbar by way of the front draft block 52 and wearblock 54 to the center sill. Clearances between the rear support block46 and the enlarged spherical butt end portion 49 are eliminated by theslack adjusting wedge 44 due to the continued force of gravity urgingthe wedge downwardly and thereby eliminating any clearances between theparts.

To transmit buff loads, the forces imposed on shank 50 are transferredby the rear support block 46 through the slack adjusting wedge 44 to therear draft lugs 42 and thereby to the center sill. The tapering surfaceof the wedge is selected so that the wedge will not retreat verticallyunder the imposed forces, thereby consistently maintaining ametal-to-metal contact relationship between all of the parts situatedbetween the rear draft lugs 42 and front draft lugs 55. Should it benecessary for the purpose of disassembling the drawbar to relieve theclamping force provided by the slack adjusting wedge 44, an instrumentsuch as a pushbar (not shown) can be inserted at the rear edge of plate56 into contact with lower edge of the wedge to displace it vertically.

The drawbar 40 in the embodiment of FIGS. 3 and 4 is formed in two shankhalves 50 interconnected by a weld joint 60 which comprises a suitablelayer of weld metal applied to a groove formed by chamfered surfaces 61on the projected ends of the shank halves. A shaft member 62 extendsbetween at the end faces of the shank halves to maintain a coaxialaligned relation during the welding process. Other means forinterconnecting the shank halves can be used, if desired.

As one can readily appreciate, if either the front load bearing block 52or the wear block 54 needed repair or replacement, the weld 60 (or otherconnecting means) which joined the oppositely-directed shanks 50 had tofirst be destroyed or otherwise removed to release the shanks 50 fromone another. The drawbar 40 could then be removed form the center sill16 by removing the sill bottom cover plate 56 which holds the front andrear load bearing blocks 52 and 46 about the enlarged spherical endportion 49 of the drawbar. Once the drawbar was removed from the sill,the front block 52 and/or the wear block 54 could then be slidablyremoved from the shank 50. Afterward, a repaired or replacement frontblock 52 and/or wear block 54 could be slid back onto the shank 50 ofthe drawbar. Upon completion of the maintenance, the drawbar assemblywas reassembled and the oppositely-directed shanks 50 were then reweldedor otherwise connected to form a continuous drawbar.

As will be seen, the construction of the drawbar assembly of the presentinvention affords much simpler and less time-consuming maintenance to beperformed on the drawbar assembly.

Also, when one considers FIGS. 5 and 6, it can be seen that virtuallythe entire surface area of the enlarged convex spherical portion 49 ofthe drawbar 40 is in contact with mating concave spherical surfacesformed on both the front and rear load bearing blocks 52 and 46. Such alarge area of surface contact leads to the creation of significantfriction between and, hence, premature wearing and failure of thosecontacting parts.

As will be described below, the construction according to the presentinvention greatly reduces the contact area between the spherical portionof the drawbar and the surfaces which contact and support the sphericalportion to thereby greatly reduce the friction therebetween and thelikelihood of premature wear and failure of those contacting parts.

Referring now to FIG. 8, there is depicted the slackless rotary drawbarassembly 140 constructed in accordance with the present invention. Theassembly 140 includes a rotary drawbar support housing 170 which iswelded or otherwise suitably secured into center sill 116. Supporthousing 170 includes a rear wall 171, top wall 172 and side walls 173and 174. As most clearly seen in FIGS. 11 and 11A, top wall 172 has anaperture 172A formed therein, the function of which is described ingreater detail hereinbelow.

Along their lower portions and toward a forward region of the supporthousing 170 each of the side walls 173 and 174 has formed thereon alaterally inwardly protruding formation. One of these formations, as canbe best seen in FIGS. 11 and 11A, is formed on side wall 174 and isrepresented by numeral 174A. An identical formation 173A is provided onside wall 173 in direct opposition to formation 174A and can be seen inFIG. 9.

A space 180 is formed at the forward end of the support housing 170between sidewalls 173 and 174. It is through space 180 that the shank150 of the drawbar passes for connection with a similar butoppositely-directed drawbar shank 150 in a manner similar to thatdepicted in FIG. 4. A concave spherical surface 182 is formed information 173A, side wall 173, top wall 172, side wall 174 and formation174A. As will be described in more detail hereinbelow, a complementaryconcave spherical surface 182A is provided on a bottom support casting190 (FIGS. 12, 12A and 12B). When properly assembled, concave sphericalsurfaces 182 and 182A form a continuous concave draft loading surface.Bottom support casting 190 is preferably fastened by nut and boltassemblies 157 to flanges 116B which project laterally outwardly fromsidewalls 116A of the "z" sill 116 as illustrated in FIG. 9.

At such time when the bottom support casting 190 is not attached to thesupport housing 170, virtually the entire bottom of the housing 170 isopen to receive an enlarged truncated convex spherical butt end portion149 of the drawbar. When it is desired to secure the drawbar within thesupport housing 170, the truncated spherical portion 149 is positionedwithin the support housing and bottom support plate 190 is fastened bynut and bolt assemblies 157 to flanges 116B of sill 116. Except where itcontacts the continuous surface formed by concave surfaces 182 and 182Aand also where it contacts a rear support block 146, the butt endportion 149 is sized so as to form clearances between its outer surfaceand the inner surfaces of the top wall 172 and side walls 173, 174 ofhousing 170.

As is most clearly seen in FIGS. 8 and 10, truncated spherical portion149 is substantially oblate spheroidal in shape with truncated upper andlower portions formed by planar upper and lower surfaces 149A and 149B.A forward, substantially hemispherical, draft load bearing surface 149Cof truncated convex spherical portion 149 is matingly received in thecontinuous ring-like concave draft load bearing surface formed byconcave surfaces 182 and 182A. A similar rearward, substantiallyhemispherical, buff load bearing surface 149D of truncated convexspherical portion 149 is matingly received in a truncated concavespherical surface 146A formed in the rear support block 146.

Assembly of the drawbar assembly 140 is as follows. Oppositely-directedends of shank halves 150 are first joined by welding or other suitablemeans to form a continuous drawbar in a manner similar to thatillustrated in FIG. 4. Then, as noted previously, the truncatedspherical portion 149 is positioned within the support housing 170through the open bottom thereof and bottom support plate 190 is thenfastened to flanges 116B of sill 116 by nut and bolt assemblies 157 inorder to retain the truncated spherical portion 149 within the housing.

Rear support block 146 is then inserted simultaneously with slackadjustment wedge 144 upwardly through the open bottom of support housing170 rearwardly of the buff load bearing surface 149D of the truncatedspherical portion 149. During this step, the slack adjustment wedge 144is held sufficiently upwardly relative to the rear support block 146 topermit unrestricted passage of the rear support block upwardly throughthe bottom of the housing until such time that its concave sphericalsurface 146B matingly receives convex spherical surface 149D. The wedge144 is held upwardly by an operator who grasps a lifting ring 200 whichis secured to the wedge and which passes through aperture 172A in topwall 172 of housing 170 as well as an aperture 116C formed in the topwall of the sill 116.

When the concave spherical surface 146B is in full contact with convexspherical surface 149D the wedge 144 is then lowered by the operator.The rear surface of the wedge 144 slides vertically relative to theforward surface of the rear wall 171 of support housing 170. Thedownward sliding of the wedge 144 under its own weight, and byadditional means to be described herebelow, causes the tapered forwardsurface thereof to cooperate with the rearward tapered surface of therear support block 146 in order to remove any slack which exists betweenthe various parts of the drawbar assembly. The system thus operates in amanner analogous to that described above with regard to the prior artwedge and rear support block system illustrated in FIGS. 5 and 6. Aswith the prior art device, the tapering surface of the wedge 144 isselected to be at an angle such that the wedge will not retreatvertically under the imposed forces, thereby consistently maintaining ametal-to-metal contact relationship between all of the parts situatedbetween and including the rear wall 171 and the concave surfaces 182 and182A of the housing 170 and bottom support casting 190, respectively.

Referring again to FIGS. 8 and 9 and also the FIGS. 11, 11A, 12, 12A and12B, it can be seen that the outer portion of the space 180 formed bysupport housing 170 and bottom support casting 190, through which shank150 extends, forms a continuous flared or tapered surface. The portionof the continuous tapered surface on support housing 170 is designatedas numeral 183 and the portion on bottom support casting 190 isdesignated as numeral 183A. The tapered surface increases the range ofmotion of the shank portion 150 of the drawbar as it moves universallyacross space 180. The angle of taper "α" ranges between about 7° and 13°with the greatest angle of taper being along the side portions of thecontinuous tapered surface to permit maximum lateral pivoting of thedrawbar along particularly sharp bends in the rail track.

Advantageous features of the bottom support casting 190 and itsconnection to the support housing 170 are illustrated in FIGS. 8, 9, 12,12A, and 12B. Casting 190 includes a base 191 having apertures 192formed in opposite ends thereof. Fasteners such as nut and boltassemblies 157 extend through apertures 192 and attach casting 190 toflanges 116B of sill 116. A rib 193 extends along the bottom surface ofthe base 191 to increase the rigidity and strength of the casting 190.Projecting upwardly from the upper surface of the base 191 are a pair ofspaced lug means 194 which extend into and closely interlock with spacedmating pockets 195 formed in the bottom surfaces of the laterallyinwardly protruding portions 173A and 174A of sidewalls 173 and 174,respectively. The interlock between lug means 194 and pockets 195provides a locking lateral, vertical and axial interconnection betweenthe casting 190 and the housing 170 to ensure the formation of a smooth,continuous concave spherical surface 182 and 182A for mating with theconvex spherical surface 149C.

In FIGS. 13 and 13A there are illustrated details of the slackadjustment wedge 144. As noted previously, the wedge has secured theretoand upwardly extending therefrom a lifting ring in the form of eyebolt200. Lifting ring 200 further serves as a wear indicator means. Thewedge 144 may further be provided, if desired, with bores 202 forreceiving biasing means such as springs (not shown). The springs wouldbear against the undersurface of the sill 116 on either lateral side ofthe aperture 116C to bias the wedge 144 downwardly to further ensurethat the wedge does not become vertically displaced and, hence, surface149D from becoming dislodged from surface 146A under buff loading, draftloading and/or axial rotation forces exerted by the drawbar.

When maximum wear has occurred in the assembly 140 to where the wedgehas "bottomed out", the wedge will have no more effect in eliminatingadditional slack. When this condition occurs, a colored wear indicatoron the vertical portion of the eyebolt will no longer be visible abovethe sill. This will indicate that the system has to be adjusted, eitherby shimming, welding, or using an oversized wedge to take up anyadditional slack. When the system has to be adjusted, the wedge can belifted up with the eyebolt to break the force between the parts. At suchtime, the rear support block 146 may be removed, followed by bottomsupport casting 190, and then the various parts of the assembly 140 canbe easily modified or replaced as necessary.

An important advantage provided by the construction of the slacklessrotary drawbar assembly 140 of the present invention is that eliminatesthe use of a separate draft bearing block assembly like blocks 52 and 54depicted in FIGS. 5 and 6. As such, the present invention advantageouslyreduces the number of parts thus simplifying and enhancing the accuracyof the assembly and disassembly of the device.

Still further, the present invention completely eliminates the need fordisconnecting the interconnected shank halves 150 in order to performmaintenance on the drawbar assembly. On the other hand, the shank halves50 of the prior art drawbar assembly 40 had to first be disconnectedfrom one another if repair or replacement of either the front draft loadbearing block 52 and/or the wear block 54 was required. As one canreadily appreciate, the present construction not only simplifiesmaintenance of the assembly but also reduces the time, labor and costsassociated therewith.

Another advantage provided by the present construction is that itinherently requires less maintenance than the prior art device disclosedin FIGS. 5 and 6. As noted at the outset, and as can be clearly seen ina comparison of the drawbar assembly of the present invention asillustrated in FIG. 8 with that of the prior art as seen in FIG. 6, onlya very small surface area of the truncated spherical portion 149 of thedrawbar is in contact with the rear support block 146 and the housing170; while in the prior art device virtually the entire outer surfacearea of the spherical end 49 of the drawbar is surrounded by and incontact with mating spherical surfaces on the draft and buff loadbearing blocks 52 and 46.

Such a large area of surface contact between spherical buff end portion49 and the mating spherical surfaces of the front draft block 52 andrear buff block 46 leads to the creation of significant friction betweenand, consequently, premature wearing and failure of those contactingparts.

By greatly reducing the area of contact between the truncated sphericalportion 149 and the housing 170 and rear support block 146, the presentconstruction thus eliminates a significant amount of damaging friction.Accordingly, the present construction reduces the frequency ofmaintenance associated with the repair or replacement of parts which aresubject to premature wear or other friction-related heat damage.

Further enhancing this effect is the provision of a through-bore 210(FIG. 8) extending between planar surfaces 149A and 149B of truncatedspherical portion 149. With such a provision, air entering from the openbottom of the housing 170 is permitted to pass into the space above theupper planar surface 149A not only through the spaces formed between theouter surface of the truncated spherical portion 149 and the side walls173, 174, but also through the through-bore 210.

Through-bore 210, in combination with the spaces formed between theouter surface of portion 149 and the side walls, 173, 174 permits air toat all times cool sizable portions of both the interior and exterior ofthe truncated spherical portion 149 to further resist friction-relatedheat damage to portion 149 as well as the parts in contact therewith.

While the present invention has been described in connection with thepreferred embodiments of the various figures, it is to be understoodthat other similar embodiments may be used or modifications andadditions may be made to the described embodiment for performing thesame function of the present invention without deviating therefrom.Therefore, the present invention should not be limited to any singleembodiment, but rather construed in breadth and scope in accordance withthe recitation of the appended claims.

I claim:
 1. A slackless rotary drawbar coupler assembly for a railwaycar having a center sill, said assembly comprising:a drawbar having ashank portion extending to an enlarged truncated spherical butt endportion defining essentially convex spherical buff and draft loadbearing surfaces, the shank portion projecting from said convexspherical draft load bearing surface; housing means secured to saidcenter sill for supporting said butt end portion therein, said housingmeans having a top wall, a rear wall and spaced side walls, said housingmeans further having an essentially entirely open bottom portion;concave surface means formed on said housing means and bearing againstsaid convex spherical draft load bearing surface for transferring draftloads therefrom to said center sill; a rear support block having atapered rear surface and a truncated concave substantially sphericalbuff load bearing surface adapted to engage with the convex buff loadbearing surface of said butt end portion; a gravity activated slackadjusting wedge for engaging the tapered surface of said rear supportblock; a detachable bottom support casting mounted to said center sillfor retaining said butt end portion within said housing means, saidbottom support casting having concave surface means formed thereon whichare alignable with said concave surface means formed on said housingmeans in order to provide a continuous concave surface which bearsagainst the convex spherical draft load bearing surface for transferringdraft loads from the convex spherical draft load bearing surface to saidcenter sill; and means for detachably securing said bottom supportcasting to said center sill.
 2. The assembly of claim 1 wherein saidbutt end portion further comprises upper and lower planar surfaces. 3.The assembly of claim 2 further comprising a through-bore passingthrough said butt end portion between said upper and lower planarsurfaces,whereby air passing through said open bottom portion of saidhousing means passes through said through-bore and through spaces formedbetween the spaced side walls of said housing means and an outer surfaceof the butt end portion to at all times directly cool both the interiorand the exterior of the butt end portion in order to resistfriction-related heat damage to the assembly.
 4. The assembly of claim 3wherein each of said side walls carries a laterally inwardly protrudingformation.
 5. The assembly of claim 4 further comprising means formed onsaid bottom support casting and on said laterally inwardly protrudingformations for providing interlocking connection between said bottomsupport casting and said laterally inwardly protruding formations. 6.The assembly of claim 5 wherein said means for providing interlockingconnection comprise lug means formed on one of said bottom supportcasting and said laterally inwardly protruding formations and matingpocket means formed on the other of said bottom support casting and saidlaterally inwardly protruding formations.
 7. The assembly of claim 6further comprising a continuous tapered surface formed on said housingmeans and said bottom support casting exteriorly of said continuousconcave surface. .Iadd.
 8. A slackless rotary drawbar coupler assemblyfor use in combination with a railway car having a center sill, saidassembly comprising:a drawbar having a shank portion extending to anenlarged truncated spherical butt end portion defining essentiallyconvex spherical buff and draft load bearing surfaces, the shank portionprojecting from said convex spherical draft load bearing surface;housing means securable to such center sill for supporting said butt endportion therein, said housing means having a top wall, a rear wall andspaced side walls, said housing means further having an essentially openbottom portion; concave surface means within said housing means adaptedto bear against said convex spherical draft load bearing surface fortransferring draft loads therebetween; a rear support block having atapered rear surface and a truncated concave substantially sphericalbuff load bearing surface adapted to engage with said convex buff loadbearing surface of said butt end portion; a gravity activated slackadjusting wedge for engaging the tapered surface of said rear supportblock; a bottom support member detachably secured to said open bottomportion of said housing means for retaining said butt end portion withinsaid housing means, said bottom support member having a concave surfacemeans which is alignable with said concave surface means within saidhousing means in order to provide a continuous concave surface adaptedto bear against the convex spherical load bearing surface fortransferring loads therebetween. .Iaddend. .Iadd.
 9. A drawbar couplerassembly according to claim 8 wherein said butt end portion furthercomprises upper and lower planar surfaces. .Iaddend. .Iadd.
 10. Aslackless rotary drawbar coupler assembly for use in combination with arailway car having a center sill, said assembly comprising:a drawbarhaving a shank portion extending to an enlarged truncated spherical buttend portion defining essentially convex spherical buff and draft loadbearing surfaces, the shank portion projecting from said convexspherical draft load bearing surface, said butt end portion having upperand lower planar surfaces; housing means securable to such center sillfor supporting said butt end portion therein, said housing means havinga top wall, a rear wall and spaced side walls, said housing meansfurther having an essentially open bottom portion; concave surface meanswithin said housing means adapted to bear against said convex sphericaldraft load bearing surface for transferring draft loads therebetween; arear support block having a tapered rear surface and a truncated concavesubstantially spherical buff load bearing surface adapted to engage withsaid convex buff load bearing surface of said butt end portion; agravity activated slack adjusting wedge for engaging the tapered surfaceof said rear support block; a bottom support member detachably securedto said open bottom portion of said housing means for retaining saidbutt end portion within said housing means, said bottom support memberhaving a concave surface means alignable with said concave surface meanswithin said housing means sufficient to provide a continuous concavesurface adapted to bear against the convex spherical draft load bearingsurface on said drawbar for transferring draft loads therebetween; and athrough-bore passing through said butt end portion between said upperand lower planar surfaces adapted to permit air circulation therethroughand reduce friction related heat within said assembly. .Iaddend. .Iadd.11. A drawbar coupler assembly according to claim 10 wherein each ofsaid sidewalls carries a laterally inwardly protruding member. .Iaddend..Iadd.12. A drawbar coupler assembly according to claim 11 furthercomprising means formed on said bottom support member and on saidlaterally inwardly protruding members for providing interlockingconnections between said bottom support member and said laterallyinwardly protruding members. .Iaddend. .Iadd.13. A drawbar couplerassembly according to claim 12 wherein said means for providinginterlocking connections comprises lug means formed on one of saidbottom support member and said laterally inwardly protruding members andmating pocket means formed on the other of said bottom support memberand said laterally inwardly protruding members. .Iaddend. .Iadd.14. Adrawbar coupler assembly according to claim 13 further comprising acontinuous tapered surface formed on said housing means and said bottomsupport member exteriorly of said continuous concave surface. .Iaddend.